预处理对园林垃圾混合物料联合厌氧发酵的影响

EFFECTS OF PRETREATMENT ON ANAEROBIC CO-DIGESTION OF GARDEN WASTE AND OTHER SUBSTRATES

采用超声、微波及碱热预处理技术强化园林垃圾、厨余垃圾与果蔬垃圾联合厌氧发酵产气性能,并以未进行预处理的实验组作为对照。结果表明:4组实验pH值在2 d内迅速降低至7.24~7.45,反应后期可稳定在7.7~8.0,表明厌氧消化系统有较强的稳定性。挥发性脂肪酸(volatile fatty acids,VFA)浓度在第2~4天内达到最大值。乙酸和丙酸是4组实验中VFA的主要成分,两者比例之和在70%以上。VFA浓度在第13天后降低到500 mg/L以下,且以乙酸为主。氨氮(TAN)浓度在前4 d内出现一定波动,随后逐渐升高至2190~2410 mg/L。游离氨氮(FAN)浓度呈先降低后增加趋势,并在第13天后逐渐趋于稳定,为144~209 mg/L。沼气中甲烷比例在第2天后均超过50%,并在第11~12天时达到最大值61.4%~63.8%。修正的Gomperts模型模拟结果表明:预处理技术可缩短反应体系厌氧产沼的适应时间,提高前期产气速率。除此之外,超声预处理与碱热预处理可显著提高基质甲烷产率,由未处理时的396 mL/g分别提高到601,536 mL/g,而微波预处理使得反应体系甲烷产量略有降低。

Ultrasound,microwave and alkali-thermal pretreatment were applied for enhancing biogas production by anaerobic co-digestion of garden waste,kitchen waste and fruit and vegetable waste.The experiment without pretreatment served as the control.The results showed that pH values of the four experiments rapidly decreased to 7.24~7.45 within 2 days and then increased to 7.7~8.0 at the end of reactions,indicating that anaerobic digestion systems were relatively stable.The concentrations of VFA reached the maximum within 2~4 days,of which acetic acid and propionic acid were the main components,accounting for more than 70%.After 13 days,VFA concentrations decreased to below 500 mg/L,and mainly acetic acid remained.There were some fluctuations of TAN concentrations during the first 4 days,which then gradually increased tO2190~2410 mg/L at the end.While the concentrations of FAN firstly decreased,then increased and stabilized to 144~209 mg/L after 13 days.The proportion of methane in biogas all exceeded 50% after the 2nd day and reached the maximum value of 61.4%~63.8% on the 11th^12th day.According to simulation results of the modified Gomperts model,pretreatments could shorten the adaption period and enhance gas production at early stage.Ultrasonic pretreatment and alkali-thermal pretreatment could significantly increase the methane yield,from 396 mL CH4/g VS to 601 mL CH4/g VS,536 mL CH4/g VS,respectively,while microwave pretreatment slightly decreased the methane yield.